The present invention relates generally to manual transmission shifters. More particularly, the invention relates to a floor mounted shifter of the type transmitting gear shift lever movements to transmission shift linkage with a pair of flexible shielded cables.
Flexible, shielded cables for transmitting push and pull forces are known in the prior art as Bowden cables. Gear shifting arrangements are found in the prior art employing one or more of these types of flexible cables as well as unshielded cables to interconnect a gear selector shifter and transmission shift linkage. Broadly, these prior art shifters may be categorized by the number and type of flexible cables employed and by the placement of the gear select lever. Prior art gear shifting arrangements employing flexible cables include shifters employing unshielded cables, shifters employing a single shielded cable with a shifter steering wheel or dashboard mounted and shifters employing two shielded cables with the shifters, steering wheel, dashboard, or floor mounted.
Those shifters employing unshielded cables suffer from several immediate disadvantages, the most obvious being that unshielded cables are capable of only transmitting forces under tension and buckle when placed under compression. Thus, these cables can transmit pulls but not pushes. Furthermore, a plurality of pulleys or the like must be provided to enable these cables to traverse an arcuate path. Shifters employing a single shielded cable, by they steering wheel mounted, or dashboard mounted shifters, suffer from the disadvantage that they either cannot employ the conventional "H" pattern shifting arrangement or they must employ at least one conventional shifting rod in combination with the cable. This one shifting rod will then suffer from the inherent disadvantages that rigid shifting linkages present in an application where the shifter is remote from the transmission.
Prior art shifters employing two shielded cables, be they shifters, steering wheel, dashboard or floor mounted, have either abandoned the conventional "H" pattern shifting arrangement or have resulted in shifting mechanisms that are relatively complex, expensive and which have a very poor feel. This lack of feel makes it difficult for the driver to determine when he has properly engaged the desired gear. Also, the prior art has never considered or solved the problems associated with employing such a two cable, floor mounted shifter to remotely control a four speed transmission in a modern automotive sedan having front wheel drive.
Furthermore, prior art shifters employing one or more flexible cables are not found featuring a reverse lockout, and particularly a push button actuated reverse lockout. A reverse lockout is a desirable feature on automotive transmission shifters that prevents accidental entry into the reverse position that could seriously damage the transmission.